308 Alternator Belt Tension (A/C, H20 Belts too!) | FerrariChat

308 Alternator Belt Tension (A/C, H20 Belts too!)

Discussion in '308/328' started by obertRo, Jul 21, 2018.

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  1. obertRo

    obertRo Formula Junior
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    #1 obertRo, Jul 21, 2018
    I've done a bunch of searching, and I'd sure like to find a definitive way to know my belts are tensioned properly. I don't want slipping, but I also don't want to wear out bearings prematurely.

    I think this is a question many of us have, and would make a good sticky if someone had a clear answer.

    If found lots of mentions about "make sure the alternator belt is Very tight" and at least one "make sure you don't overtighten the alternator belt" but I find almost no "data" or non-subjective information.

    Right now, I can "pluck" each of my 3 belts, and get a musical note, but how high/low should the pitch be? And of course this note varies for the same belt on the different segments.

    I've always done this by feel on my American and British cars, but of course this is a Ferrari...

    Here's a video link showing me plucking the belts. The sound in the video is duller than real life.


    Thanks!
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  2. StuR

    StuR Formula Junior

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    #2 StuR, Jul 21, 2018
    I thought the handbook (mondi QV) has deflection and rates for belt tensioning, at least for alternator?

    I’ll dig it out and re-check..


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  3. StuR

    StuR Formula Junior

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    #3 StuR, Jul 21, 2018
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  4. thorn

    thorn F1 Rookie
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    #4 thorn, Jul 21, 2018
    I just do it by belt deflection/twist.
     
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  5. lm2504me

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    #5 lm2504me, Jul 21, 2018
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  6. StuR

    StuR Formula Junior

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    #6 StuR, Jul 21, 2018
    And a cold engine!! Made that mistake and got a frightening squeal.


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  7. obertRo

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    #7 obertRo, Jul 21, 2018
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  8. StuR

    StuR Formula Junior

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    #8 StuR, Jul 21, 2018
    LOL.

    I wonder if yours is the original book? I guess you need the later years manual - I assume they updated it. I have a workshop manual for the WV too - somewhere. It may well be in that. If I can find it I’ll post it. Meanwhile One of the other guys may have the 3 belt diagram. I would hope FMA would also tell you from their old service schedules. It’s no skin off their nose to share now.

    I suspect many experts just ‘know’ and use experience. I’m one of those mortals who likes (and needs) it written down!!


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  9. obertRo

    obertRo Formula Junior
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    #9 obertRo, Jul 21, 2018
    Thanks again, Stu. This is an 85 Manual, but I think Ferrari wasn't exactly careful to update these things!


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  10. StuR

    StuR Formula Junior

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    #10 StuR, Jul 21, 2018
    Yeah I think they way some where stickered up, etc suggests it wasn’t clear which cars had bits of earlier or later variants. Add to that the impression that some parts bins got discovered and reused, its all about adhoc.

    Always thought it strange that Ferrari expected its drivers to be setting belt tension at the roadside. Useful on the millemiglia perhaps.... or if your recovery chap turned up on a Sunday when the dealer was closed?!?

    Let’s see if an 86 turns up!!!


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  11. obertRo

    obertRo Formula Junior
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    #11 obertRo, Jul 21, 2018
    Last edited: Jul 21, 2018
    Okay, I bought a very inexpensive Belt Tension Tester; the Gates Krikit. Less than $15!
    With it I could measure the A/C tension (right at 50# thank you Ferrari gods! :)) quite easily. This is B in the diagram Stu posted.
    And from the generic tensions chart included with the tester, I suppose I can try the others (marked with arrows). I would prefer numbers from Ferrari, but at least this is something quantitive.

    I will see how this goes and post photos of the testing.
    Meanwhile, here is the tester and the chart:


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  12. lm2504me

    lm2504me Formula 3
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    #12 lm2504me, Jul 21, 2018
    I tried the Krikit and then I applied the force to obtain the correct gap per OM, it was way off. So, I passed on the Krikit and used my Gates tool to apply the required force and measured the movement per the OM.
     
  13. StuR

    StuR Formula Junior

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    #13 StuR, Jul 21, 2018
    Is yours a 2 or 3 belt?


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  14. obertRo

    obertRo Formula Junior
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    #14 obertRo, Jul 21, 2018
    Okay, so the Gates Krikit told me the Alternator Belt was at 50#--but it should be 70#--so I adjusted that okay. It "plucks" a significantly higher pitch note now, too.
    Richard I have got to get a pulley tension device like yours. Using the quick clamp was okay up to 50 pounds but got mighty tough after that. I'd rather leave it in the wood shop.

    Now...the Krikit really doesn't want to fit the Water Pump Belt. The A/C idler pulley interferes, and the gap is just too small. I think I need the kind of in-line tester Richard shows. I guess I'll have to wait for Amazon. Then I'll report back.


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  15. lm2504me

    lm2504me Formula 3
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    #15 lm2504me, Jul 21, 2018
    You may want use the inline (Gates push tester) to verify you did not over tighten the alternator belt per the OM specs.
     
  16. obertRo

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    #16 obertRo, Jul 21, 2018
    Ummm, I just realized that the Gates Push Tester is not going to help me with the Alternator or Water Pump Belts as I don't have OM specs for them.

    If I decide to use the tensions given in the Gates Chart, (60# for Water Pump Belt and 70# for Alternator Belt) then I need a tester that will tell me overall tension. Plus the device must fit into the tight spaces.

    Possibly something like this? https://www.ebay.com/i/173407143134?chn=ps


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  17. StuR

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    #17 StuR, Jul 21, 2018
    Yeah I don’t think the Type 150 is still made, but wonder what Gates would recommend....
    committed now to finding 3 belt tension figures!!!!


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  18. lm2504me

    lm2504me Formula 3
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    #18 lm2504me, Jul 21, 2018
  19. lm2504me

    lm2504me Formula 3
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    #19 lm2504me, Jul 21, 2018
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  20. StuR

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    #20 StuR, Jul 21, 2018
    Hurrah - I knew we’d get them.


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  21. lm2504me

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    #21 lm2504me, Jul 21, 2018
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  22. obertRo

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    #22 obertRo, Jul 21, 2018
    Awesome, thank you!
    Now the "pencil type" Gates gauge will work!
     
  23. lm2504me

    lm2504me Formula 3
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    #23 lm2504me, Jul 21, 2018
    You are welcome. Have fun!!!
     
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  24. lm2504me

    lm2504me Formula 3
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    #24 lm2504me, Jul 21, 2018
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  25. Lawrence Coppari

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    #25 Lawrence Coppari, Jul 22, 2018
    Just tighten it enough so that it does not squeal when you first start the car and turn on accessories. As the engine warms up the belts will tighten more. Few metals expand more than aluminum when heated. Overtightening puts excessive load on the bearings. The Krikit tool works fine. I have used it on my Porsche cam belt for over 20 years.
     
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